Difference between OCA/H and MDA/H?

[babyboeing400]

What's the difference between these 2? i have some idea that with OCA/H,one has to descend to the OCA/H at that specific point as laid out in the app plate..whilst you can descend onto MDA/H earlier and flying level thereafter until the MaPT...is it correct?

[FlightDetent]

Not at all. My reply to you here.

[180 Too Fower]

MDA/H is applied to the "Instrument Approach"
OCA/H is applied to the "Visual Manoeuvring"

As I understand it.....If you are flying an approach that requires a "Circle to Land" you fly down to MDA/H.....if visual and in the "Circling Area" you can desend to "Circling Minima" or in some cases OCA/H - which is the lowest minima for VISUAL manoeuver

[Clandestino]

Both OCA/H and MDA/H are related to instrument approaches - precision, non precision and visual manouvering (despite its name it's IFR procedure). MDA/H is derived from OCA/H by adding the margin, which is based on operational consideration of:

-category of operation
-ground/airborne equipment characteristics
-crew qualifications
-aircraft performance
-meteorological conditions
-aerodrome characteristics
-terrain profile/radio altimeter
-pressure error/pressure altimeter
-location of guidance aid relative to runway
-etc.

Descending to MDA and flying level to MAPt is simply not a way to handle modern transport category airplane. While it's not unlawful to do so, my SOP prohibits leveling off at MDA and go-arond must be started at VDP latest. Anyway, intentional descent to OCA/H is a big no-no if your margin is greater than zero.

[FlightDetent]

Only to add to Clandestino's:

MDA/H and DA/H is minima. OCA/H is only one value that enters the equation to calculate those. If you treat OCA/H as minima you will use incorrect number and knowingly exclude other important information. Which is not only illegal but also will make you hurt somebody one day.

FD

[babyboeing400]

thanks a lot guys..that really helped a lot..